高浓缩倍率冷却水中304不锈钢耐蚀性能研究

高浓缩冷却水中离子浓度的提高对冷却管的耐蚀性能会产生影响。采用某电厂循环水补充水,研究了304不锈钢在不同浓缩倍率的冷却水、经某低磷药剂处理的冷却水,以及含低磷药剂并加酸处理的冷却水中的耐蚀性能。结果显示:在未经处理的冷却水中,随着浓缩倍率的提高,不锈钢的过钝化电位或点蚀电位下降,点蚀敏感性增大;冷却水中加入低磷药剂时,不锈钢耐蚀性能随着药剂浓度的增加而提高;当含低磷药剂的冷却水经进一步加酸处理时,不锈钢的耐蚀性能也得到进一步的增强。通过不同处理引起的冷却水p H值及阴离子浓度变化,讨论了加阻垢剂和加酸处理提高冷却水中黄铜耐蚀性能的原因。     

聚亚烷基二醇——全合成高性能工业润滑剂基础油

文章介绍了全合成高性能工业润滑剂基础油聚亚烷基二醇的特性,聚亚烷基二醇具有低牵引系数和摩擦系数、优异的润滑性能、高黏度指数、低毒、可生物降解、良好的低温流动性、优良的抗氧化和热稳定性,几乎不产生残渣和油泥。可以用来生产高性能的齿轮油、液压油、压缩机油等全合成润滑剂,此外,它还可以生产食品级润滑剂。随着人们对环境友好和绿色产品意识的提高和政府对环境保护的重视,聚亚烷基二醇基础油在润滑剂工业领域将会得到广泛应用。     

Untersuchungen zum Einfluss des Stickstoffs auf das Lochkorrosionsverhalten hochlegierter austenitischer Cr‐Ni‐Mo‐Stähle

Investigation of the influence of nitrogen on the pitting corrosion of high alloyed austenitic Cr‐Ni‐Mo‐steels Austenitic stainless steels (18% Cr, 12% Ni, Mo gradation between 0.5 to 3.6%) had been gas‐nitrided. By stepwise removal, samples could be prepared with various surface content of nitrogen up to 0.45%. The susceptibility against pitting corrosion of these samples had been tested by two methods: – determination of the stable pitting potential in 0.5 M NaCl at 25°C – determination of the critical pitting temperature in artificial sea water (DIN 81249‐4) The influence of nitrogen to both determined parameter can be described well by PRE = Cr + 3,3 · Mo + 25 · N That means for the investigated steel composition and the used corrosion system there is no influence of molybdenum on the effectiveness of nitrogen.     

热处理对铝锂合金在NaCl水溶液中腐蚀行为的影响

对铝锂合金在热轧、固溶淬火后自然时效和不同时间人工时效后测定了在３．５％ＮａＣｌ水溶液中的平均腐蚀速率，观察了腐蚀形成，结果表明，合金的平均腐蚀速率较大，在含Ｃｌ＾－介质中易发生局部腐蚀，透射电镜观察结果表明，延长时效时间，合金昌粒中Ｔ１相增多，δ＇相减少，晶界富铜相增多，无沉淀带加宽，因而加剧了点蚀和沿晶腐蚀。     

小直径水平扩壶爆破技术在路堑开挖中的应用

通过小孔径水平孔扩壶爆破技术在杭金衢高速公路开挖工程中的实际应用,文章提出了该技术的爆破参数设计方法、施工工艺及应用条件,可供类似工程参考.     

Initiation and propagation of stainless steel pitting corrosion under heat flux

An effect of heat flux on initiation and propagation of pitting corrosion of austenitic stainless steel in chloride environment has been studied using electrochemical and exposure methods. The experiments were performed at constant surface temperature of 60°C and heat flux from ? 15 to + 74 kW m^?2. The presence of heat flux from metal to solution shifted the breakdown potential towards noble values and lowered the pit density, whereas the pit propagation rate increased. Presence of maximum heat flux caused, in comparison with isothermal conditions, increase of the breakdown potential by approx. 100 mV, reduction of pit density by 30% and increase of the average pit depth by 40%. The positive effect of heat flux from metal to solution was given mainly by improving the protective ability of the passive film, as the amount of oxygen available at the metal surface increased. With a smaller significance, the effect of intensified mass transfer, which made accumulation of the chloride ions on the surface more difficult, occurred.     

Lochkorrosionsverhalten von Auftragschweißungen – Schweißlagen‐ und Oberflächeneffekte –

Pitting corrosion behaviour of built‐up welds – Effects of welding layers and tarnish – The pitting corrosion resistance of nickel based deposition welds on a superduplex steel made by active‐gas metal pulsed‐arc welding was studied. Therefore the determination of the CPT (Critical Pitting Temperature) should be carried out corresponding to ASTM G 48 C. However an unexpectedly low resistance of the built‐up welds also at multilayer order was noticed. After visual assessment of the examined specimens a significant effect of the surface condition was assumed. Because the CPT determination according to ASTM does not allow any statement about the corrosion process, this method was not suitable to characterize the corrosion system. For this reason a new method was applied to clarify the causes of the low corrosion resistance. This method determines the CPT with the help of the electrochemical current noise under the same conditions demanded in ASTM G 48 C. The temperature is increased continuously and the characteristic parameters of the system are recorded and evaluated objectively within short time. So it was possible to see the influence of the surface condition on the pitting corrosion behaviour of the examined specimens. The required parameters to the post‐processing of the deposition welds were determined. The comparison of the results show that the surface tarnish formed after the shielded arc welding process influences the pitting corrosion resistance negatively. After its elimination the CPT could be determined in dependence of the welding layers.     

Einfluss höchster Reinheitsgrade auf die Lochkorrosionseigenschaften austenitischer Stähle

Influence of highest degree of cleanliness on the pitting corrosion behaviour of austenitic steels Stainless steel grades of the type material. no. 1.4401, produced in an industrial scale, have been vacuum arc re‐melted up to three times to achieve lowest inclusion contents. These materials have been corrosion tested to get information about the influence of non‐metallic inclusion content on pitting corrosion behaviour. By the use of potentiodynamic polarisation curves on basis of ASTM G61‐86 a clear effect of steel cleanliness was detected. The highest degree of cleanliness and best corrosion behaviour has been achieved with vacuum arc re‐melting material where non‐metallic inclusions are moved to the ingot surface area and minimum gas contents and micro‐segregations are gained.     

马氏体相变对孔蚀闭塞区化学和电化学行为的影响

采用模拟闭塞电池法和模拟闭塞溶液法研究了奥氏体304不锈钢形变诱发马氏体相变对孔蚀闭塞区化学和电化学行为的影响。为了模拟闭塞区内外间的电偶电流，对试件通入电流进行阳极极化。结果表明，与未形变的304不锈钢的试验结果相比，随着马氏体含量的增加，闭塞区溶液pH值下降，Cl^-迁入闭塞区的量更多。马氏体相的存在增强了材料的电化学活性，使其在模拟闭塞溶液中的自腐蚀电位负移，维钝电流密度增加，加速了闭塞区金属阳极溶解，促进了孔蚀的发展。     

水压机柱塞失效分析

用光学显微镜，扫描电镜和能谱仪对水压机柱塞表面孔坑，沟槽进行了分析，结果表明，由于夹杂物（尤其是表层夹杂物）与块状铁素体的存在以及淬硬层分布不均匀，使柱塞在使用过程中出现点蚀，并在高压水冲击下形成沟槽，导致柱塞密封失效。